Differential pressure controlled flow valve



Aug. l1, 1942.

E. D. PARKER DIFFERENTIAL-PRESSURE CONTROLLED FLOW VALVE Filed oct. 2,'1939 fdl A TTORNEY Patented Aug. 11, 1942 DIFFERENTIAL PRESSURECONTROLLED FLOW VALVE Edward D. Parker, Glendale, Calif., assignor toThe Guiberson Corporation, Dallas, Tex., a corporation of DelawareApplication October 2, 1939, Serial No. 297,540

(Cl. S-233) 3 Claims.

This invention relates generally to gas lift apparatus employed in deepwells for production purposes and is more particularly directed to whatis commonly referred to as a ow valve.V

It is the principal object of the present invention to provide animproved type of flow valve for inducing pressure gas into a column ofwell fluid and automatically operable to closed or open positions underpredetermined differential pressure conditions between said gas and saidfluid column at said valve, and to provide a valve of the piston typeWhich is subjected at opposite `ends to such pressure conditions and isprovided With tension means for controlling the differential under whichsaid valve functions, said tension means being replaceable by othersimilar tension means of different tension value to vary saiddifferential factor.

One form which the invention may assume is exemplified in the followingdescription and illustrated by way of example in the accompanyingdrawing, in which:

Fig. 1 is a semi-diagrammatic longitudinal section through a wellinstallation illustrating one use of my improved flow valve.

Fig. 2 is an enlarged vertical section through a valve unit -constructedin accordance with the present invention.

Fig. 3 is a transverse section taken on the line III-III of Fig. 2.

Fig. 4 is a 'transverse section taken on the line IV-IV of Fig. 2.

In the example illustrated in Fig. 1, A designates the well casing and Bdesignates the tubing string which, at the surface, communicates withthe production line Ill and is provided with a pressure gauge II. Theupper end of the casing Aris closed in the usual manner and is providedWitha pressure gauge I2. the upper end of the casing is a pressure lineI3 by means of which gas or air under pressure may be pumped into thecasing.

The tubing string B is, near its lower end, provided with a standingvalve I4 and with a screen section I5 and, in instances where it isnecessary or desirable, a packer I6 may be positioned between the tubingand the interior of the casing at a point above said screen.

C designates the ow valve units which are incorporated in the tubingstring B and form detachable sections thereof, each valve unit providinga production now passage of a uniform diameter substantially equal tothe internal diameter of the standard tubing sections formingCommunicating with the balance of the tubing string, whereby there isprovided an unobstructed tubing string affording full flow of the wellfluid and permitting swabbing and such other operations as may benecessary or desirable.

Referring to Figs. 2, 3 and 4 of the drawing, it will be observed thatthe valve unit C comprises a main body which, primarily for economy ofmanufacture, is formed of a relatively short length of tubing IIsuitably screw-threaded at its opposite ends for incorporation in thetubing string B. At one side on this tubular body Il there is disposed ahead-guide I8 and a relatively spaced tail-guide I9 vertically alignedtherewith, said guides being preferably formed of separate pieces weldedor otherwise securely xed to the body II to function as rigid partsthereof. One of the functions of these head and tail guides is to safelyguide the tubing string in its installation in and withdrawal from thewell casing and -to protect the valve mechanism which is supportedbetween said guides.

The valve mechanism is disposed closely adjacent and parallel to theexterior surface of the tubular body I 'I and includes a tubular valvebody 20 which is screw-threaded into the underside of the head-guide I8with its bore providing a valve chamber whose upper end is incommunication with a gas passage 2l formed in said head-guide andthrough the wall of the tubing I1 to discharge into the tubing string.

Secured in the upper end of said valve body 20, preferably by a drivefit therein, is an annularvalve seat 22 and at an appreciable distancebelow said seat said body is provided with one or more transverse gasinlet ports 23 which communicate with the valve chamber and with theannular space between the tubing string and the interior of the wellcasing.

The lower portion of the valve body 2B is counterbored to provide aspring chamber 24 and is provided with a terminal cap 25 screw-threadedthereon, the lower end of said cap having a central recess formedtherein for engagement by a retaining screw 25 which is screw-threadedin the tail-guide I9. This retaining screw maintains the lower end Aofthe valve body against transverse displacement and also prevents anaccidental unscrewing of the valve body from the head-guide I8, while atthe same time providing a means which may be actuated to release suchrestraint so that the valve body 20 and its contained parts may beeasily detached from the main body of the unit for repair orreplacement.

Sldable within the bore of the valve body, below the valve seat 22, is apiston valve 21 whose upper end is adapted to engage said valve seat toclose the gas passage 2l. The lower end of the valve 21 is enlarged toprovide a piston 28 which is slidable within the spring chamber 24 andprovides on said valve an annular spring abutment shoulder. A coilcompression spring 29 surrounds the valve 21 and is disposed within thespring chamber to engage the upper wall thereof and the piston 28 so asto mechanically exert a pressure on the valve normally tending totranslate it downwardly to the open position shown in Fig. 2, in whichposition its upper valve end will be below the gas inlet ports 23 andits lower end will seat against the terminal cap 25.

The terminal cap 25 is centrally recessed downwardly from its upperinterior surface, as. at 3D, and is provided with one or more transversepassages 3I intersecting said recess so as to permit entrance ofexterior gas into the lower'end of the valve body bore and thus subjectthe valve to the pressure of the gas in the well casing, with such gaspressure being exerted in a valve closing direction in opposition toreverse pressure exerted by the valve spring and by such fluid or gaspressure as may be exerted upon the opposite or valving end of saidvalve.

Preparatory to placing a well on production a series of the ilow valveunits C will be installed in the tubing string B at relatively spacedintervals of about three hundred to four hundred feet, depending uponthe characteristics and production requirements of the particular wellinvolved, with the uppermost unit submerged a predetermined distancebelow the normal static fluid level in the well.

With the apparatus properly installed the well, as indicated in Fig. 1,the several ilow valves are normally maintained open, as shown .in Fig.2, by their respective springs which determine the pressure differentialunder which they function.

To place the well on production compressed gas will be admitted into theannular space between the well casing and the string of tubing, fromwhich space said pressure gas will beentrained into the tubingareafthrough the respective iiow valves under control of the pressuredifferential established by the valvesprings.

Each of the flow valves will operate independently of the others andwill provide an automatically functioning means for. transferringpressure gas from the casing area into the tubing area when pressureconditions Vwithin the tubing at the valve level equal the diierencebetween the casing pressure and the tension pressure of the valvespring.

If the spring 29 is so constructed as to impart a downward force of onehundred pounds-on the valve stem 2, that force is effective as adifferential pressure between the casing and the tubing pressures.Therefore, if the casing pressure varies, as it will under anyoperation, from two hundred pounds to one thousand pounds, thecontrolling pressure under the valve stem will keep the valve in seatedposition and closed against the transfer of gas from the casing to thetubing.

To open a closed valve, it is a requirement" that a pressure (uid heador otherwise) be obtained within the tubing, above the particular valvein question, equal to the casing pressure minus the spring differentialpressure.

For example, let it be assumed that'the upper- 75- most flow valve C inthe tubing string B is located one hundred feet below the normal staticfluid level which is the same both within the tubing and within thecasing A.

Assuming also that the well fluid is of that gravity which will impart ahead pressure of .35 pound per foot of height, then the head pressure ofthe fluid standing in the tubing above said top valve Will total onehundred feet multiplied by .35 pound or thirty-live pounds.

Considering further that the size of the annulus area between the casingand the tubing is ve times the area of the tubing, then as pressure gasis admitted to the casing, the well iluid in the casing must betransferred into the tubing (or back into the formation when the packerI6 is not employed) Since the valve under consideration is one hundredfeet below the static uid level, the pressure necessary to move the uidfrom the annulus must be sufficient to support a fluid column in thetubing extending five hundred feet above the static fluid level or sixhundred feet above said valve. This six hundred feet of uid in thetubing will then present a head pressure of six hundred feet times .35pound or two hundred ten pounds. This two hundred ten pounds headpressure will then represent the load requirement on the valve and thepressure within the casing will have to be increased only slightly topermit the valve to be opened.

If the differential built into the valve spring 29 is one hundredpounds, the valve 21 will open when the pressure load in the tubing isone hundred pounds less than the pressure in the casing.

When the valve is opened under these-pressure conditions, the load oftwo hundred ten pounds is engaged by a force of three hundred ten poundsand must move upwards, that being the line or direction of leastresistance in the tubing. As soon as the inertia of this load has beenovercome, it will require less pressure to keep it moving, and as thepressure cannot be reduced, there will be an increase in velocity. Thisincrease in velocity of the upwardly moving fluid column in the tubingwill be a uniform accelerated velocity and a pressure drop will occuracross the valve seat. When the pressure drop at that point is equal tothe differential force of the valve spring 29, ,the ga's pressureexerted upon the lower piston end 28 of 'thevalve 21 will force thevalve to its upper position, closing the gas inlet ports 23 and engagingthe valve seat 22 and arresting the injection of gas through the gaspassage 2| and into the tubing string;

With the valve thus closed, the operating cycle thereof is completed,and as the uid continues to rise in the tubing, this top valve will bein operation as frequently as pressure conditions within the tubing areequal tothe requirements of that valve.

The valves below the top or uppermost valve become effective as theiluid level in the well casing is lowered, each valve operatingindependently of all others. In this manner it is possible to flow awell at any predetermined rate of production by controlling the casingpressures applied.

Attention is directed to the fact that the gas inlet ports 23 are spaceda considerable distance from the valve seat 22. This provides an earlycut-off of the gas inlet ports 23 and thus promotes a relatively quickclosing action of the valve, and also prevents certain eroding effectsofthe pressure gas which might otherwise cause trouble through leakage.

From the foregoing it will be understood by those skilled in the artthat my improved valve, being automatically operable by differentialpressure conditions of the lifting gas and the production column at thevalve, will provide a flow means fully capable of meeting various owrequirements incident to the gas lift method of production, and that, byreason of the fact that the controlling differential factor, aspredetermined by the valve spring tension, may be varied, said valve mayeasily and quickly be conditioned to meet definite requirementsdepending not only on the characteristics of a particular well, but alsoupon the producers requirements as to the allowable production rate asdetermined by operating conditions or prorated allowables.

While the device herein illustrated and described is a preferred form ofVembodiment of the invention, it is to be understood that variouschanges of structure may be made by those skilled in the art withoutdeparting from the spirit of the invention as dened in the appendedclaims.

Having thus described my invention, whatA I claim and desire to secureby Letters Patent is:

1. In combination with a well tubing and casing with a compressed airchamber therebetween, a flow valve, a housing therefor having relativelylarge and small cylindrical portions and having a shoulder between saidportions, ports extending from the compressed air chamber to the smallcylindrical portion, and a port leading from one end of the smallcylindrical portion into the tubing, a piston having a close t with thesmall cylindrical portion and slidable therein so as to cover or uncoversaid ports leading to the compressed air chamber, a head on the piston,said head having a close fit with the large cylindrical portion, meanswhereby the outer end of said head is exposed to the pressures in thecompressed air chamber, and a spring interposed between the head and thesaid shoulder.

2. In combination with a well tubing and casing, with a compressed airchamber therebetween, a housing, a small piston chamber in one end ofsaid housing and a communicating large chamber in the other end thereof,a shoulder at the end of the large chamber adjacent the smallpistonrcham-ber, a piston slidable in the small piston chamber andhaving a snug fit therewith and exiting into the large chamber, a headin said large chamber and on said piston, said head making a snug t with=the large chamber, a spring interposed in said large chamber betweenthe shoulder and said head, means whereby the outer portion of said headis exposed to the pressures in the compressed air chamber, portsextending from the compressed air chamber into the small piston chamberimmediately above the end of said piston when it is in extreme openposition, and adapted to -be closed by said piston when the piston is inclosed position and a passageway leading from the small piston chamberinto the tubing.

3. In combination with a well tubing and casing with a compressed airchamber therebetween, a ow valve having a spring chamber and a pistonchamber, a piston slidable in said piston chamber and extending intosaid spring chamber, a head on one end of saidpiston and making a snugfit with Said spring chamber, so as to prevent iluid from passing intosaid spring chamber, ports leading from said compressed air chamber intosaid piston chamber, a spring in said spring chamber and acting on saidhead to move said piston, so as to open said ports, a passageway leadingfrom the piston chamber into the well tubing so that pressures in thetubing will be exerted on the piston, said spring yielding to allow thepiston to close said ports When the casing pressure exceeds the tubingpressure plus .the tension of the spring and the weight of the piston.

EDWARD D. PARKER.

